Look through two pieces of glass, one regular and one with low iron content. You will certainly see a difference between the two pieces of glass you are looking through. The regular glass will appear to be slightly green, while the one with low iron content will be clear, or white. This type of low iron float glass is also called ultra white. Low iron float glass can be tempered to increase it’s strength. It is done in an oven that will make the glass up to four times stronger. Tempered glass will break into small pieces to reduce risk of injury.